1. Field of the Invention
The present invention relates to a semiconductor device and a method of manufacturing thereof, and in particular, relates to a semiconductor device of a double-sided electrode structure and a method of manufacturing thereof.
2. Description of the Related Art
Recently, due to electronic devices such as cell phones and the like being made more compact, developments in three-dimensional packaging techniques which have higher packaging densities have advanced. Among these three-dimensional packaging techniques, a method called package-on-package (POP), in which a package is layered on another one package, is promising. A package of a double-sided electrode structure (a double-sided electrode package) is used in POP. A double-sided electrode package requires an internal wire connected to a semiconductor chip, a through electrode connecting the internal wire and an electrode at the package surface side, and a through electrode connecting the internal wire and an electrode at the package reverse side.
Double-sided electrode packages of various structures have conventionally been proposed. For example, Japanese Patent Application Laid-Open (JP-A) No. 2002-158312 discloses a resin-sealed type double-sided electrode package. In this double-sided electrode package, a through electrode is provided at a sealing resin layer that seals a semiconductor chip, and a surface side electrode and an internal wire are connected via this through electrode.
Further, a lead frame type double-sided electrode package is disclosed in JP-A No. 2003-249604. In this package, a portion of an internal lead is exposed at the exterior of a resin sealing material, and the surface and the reverse of the internal lead are made to be external electrodes. Here, the internal lead functions as a through electrode.
Moreover, a ball grid array (BGA) type double-sided electrode package is disclosed in JP-A No. 2005-235824. In this package, a stepped portion is provided at a package substrate. The end portion of an electrode for wire bonding is exposed at the stepped portion. This end portion and a surface side or reverse side electrode are connected by a through electrode which passes-through the package substrate.
In order to mount these double-sided electrode packages at a high density, the individual packages must be made to be thin. For example, in JP-A No. 2005-235824, the package is made to be thin by providing the stepped portion at the package substrate and mechanically grinding the package substrate from the reverse side.
However, in the structures of conventional double-sided electrode packages, the surface side electrode is not disposed in an arbitrary layout, and adaptability in connecting the top and bottom packages is lacking. Further, the sealing resin layer is formed by a transfer method, but in a transfer method, molding is carried out by using a mold, and it is therefore difficult to form the sealing resin layer to be thin.